I know this is does not seem like the best place to put this but I know alot of Honda owners own and work on older Chevys as well. I was one of those. I need help with my 1989 Chevy Suburban. I'm having horrible problems with idle and surging. I've replaced a list of parts and have narrowed it down to the Manifold Absolute Pressure sensor (altitude sensor) and Fuel pump. I've ordered a replacement MAP sensor but I need to know which GPH rated fuel pump to get. The truck has a 350 V8 with GM's Throttle body fuel injection and a 700r4 Auto transmission. A/C and heat included. There are 2 pumps i can get: a 20gph and a 43 gph rated pump.
I believe my tank is a 31 gallon tank. Help would be much appreciated. Thanks guys, here's more info if needed:
Replaced parts: Drive belt, Distributor cap, rotor, sparkplug wires, coolant temp sensor, EGR valve, EGR solenoid, vacuum hoses, 02 sensor, rebuilt throttle body and injectors, TPS, IAC, Catalytic converter, Fuel pump relay, Fuel pump fuse, Checked all fuses, fuel filter, Checked all grounds including ECM to block ground, alternator and battery are good, ECM and PROM all check out.

 

why not get a factory ac delco pump?

 

Well that is the issue. There's 2 electric AC Delco pumps that are presented for this model: A 20 and a 43 Gallon per hour model. I'm just not sure which one I need and if I get one too powerful it can blow the seals out from around my tbi injectors. Lord knows I don't want to have to rebuild that again. I'm wondering if the 43 GPH one is for the 454 model and not the 350 model.

 

I'm confused...but my Chevy is like 50 years old.

GPH is a "volume" measure and not a PSI. So more volume at the same PSI isn't going to change much.

Not sure of the body style, pretty sure back them GM couldn't figure out what to do with those,,,,,R vs V.....or was it C vs V (might have only been pick ups).

Airtex is showing the same E3633S....Delphi HP10021 for the same....or at leat at my lame idea of looking up the pump with just the info given

 

Thank you that's what I needed to know! I figured the flowrate wouldn't normally matter but I wanted to check because all of the pumps run the same psi required for the truck but all the flowrates were different. I'm used to working with my '79 Chevy vans manual fuel system requirements and not mom's '89 electric fuel system's requirements XD. I remember you from a while back, I learned a bit from you months back but couldn't remember your screen name to ask you about this stuff :P So as long as a pump runs 12psi of pressure it doesn't matter if it has a 20 or a 43 gph flowrate?

 

Again, don;t quite have all of the details.....first I thought TBI ran a higher PSI than 12 but it has been a long time since I messed with these.

Going with a higher flow rate should not matter, again the PSI is the same. I wouldn't go with a lower flow/GPH.

Again, just using general understanding of the system and a quick look online for replacement pumps - rockauto. General tells me the higher GPH will not be an issue since there is no major change in PSI, then on rockauto I saw the same aftermarket pump listed for the r or v series chassis.

What AC Delco part numbers are getting? I have some contacts in the automotive aftermarket that might be able to give me more spec's on them.

 

I'm not sure what's in the tank yet as I haven't taken it out yet. I don't have any casting or OEM numbers to go on yet. I do know 9-13 psi are the magic numbers for the pre-96 non vortec tbi engines (350s and 305s). If I wanted a pump fast and quick my local oreillys autoparts has a precision brand pump (E18001) that's a 12psi at 43gph flowrate rated pump and their cheaper house brand one Masterpro (E16007) thats a 12psi at 20gph. I'm kind of weiry of new AC Delco products or I'd consider this one https://www.amazon.com/ACDelco-EP386.../dp/B000C9PA54 But Nowdays I feel I'd trust Precision over them I'm afraid. What do you think? These TBI injectors move 55lbs/hr Just a tidbit in case you wanted to know that for future reference.

 

I do agree with you about the quality of the newer AC Delco stuff, so I'd probably go with the Precision brand pump. Having replaced Delco pumps in the past, getting the tank down (they usually quit when full or near full) and out is the hard part of the job. The Precision pump also carries a lifetime warranty (doesn't include labor though). Most of these pumps are rotary, and last a long time, and as you've found yours has already lasted quite some time. The "gph" rating of the pump isn't that big a deal when dealing with low pressure TBI systems, but if it'll make you feel better, go with the higher gph.
I just don't understand why some people get all wrapped up in ghp ratings, or how much fuel will flow thru an injector when dealing with older systems. The ECU controls the injector "hold" time. I only say that, as I have a really old air cooled VW engine here (2 actually) that still have their FI system still intact, and they use low impedence injectors that flow very well at a pressure between 28 and 32 psi. Above 32 psi, they fail to close and the flow rate drops off. Below 28 psi, and the engine won't hardly run. We've been using the Precision brand E16020 pump with them (spec'd for an 85 to 89 ranger) with good results (I'm a member of the Samba) in the VW community.
Sorry for getting a little off topic, but I do have a couple of GM mini vans here, and a buddy of mine still has his 91 GMC that he bought brand new.
If you want more info, I'd suggest going to Chevy Talk, as there's a lot of GM people there.- I hope this helps.

 

Thanks so much for Everyones input, you guys are awesome! Its gonna get cold real fast in a few days so I'm going to hit it hard and if the precision pump is in stock local then I'll get it. If not, I found a good Carter I can order. I'll post what numbers I find or if I run into anything unexpected. I think I'll get replacement flexible metal lines for where the fuel lines go from the sender to body lines just in case the ones on there have pinholes. (Saw that in another forum)

 

usually the is a code on the tag in glove box or wherever that would distinguish things like that